Process for the preparation of sulfur- and phosphorus-containing organosilicon compounds

ABSTRACT

Process for the preparation of sulfur- and phosphorus-containing compounds of the formula: 
     
       
         [R 1   n (R 2 O) 3−n —Si—Alk—S—] 3 P═S 
       
     
     in which halogen-containing silanes of the formula R 1   n (R 2 O) 3−n —Si—Alk—Hal are reacted with phosphorus pentasulfide (P 4 S 10 ) and a metal sulfide.

INTRODUCTION AND BACKGROUND

The present invention relates to a process for the preparation ofsulfur- and phosphorus-containing organosilicon compounds.

German application DE 2658368 C2 discloses compounds of the formula

[R¹ _(n)(R²O)_(3−n)—Si—Alk—S—]₃P═S,

in which Alk denotes an alkylene group having 2 to 4 carbon atoms, R¹,R² denote an alkyl group having 1 to 5 carbon atoms, a cycloalkyl grouphaving 5 to 8 carbon atoms, a phenyl group, a benzyl group or the2-methoxyethyl group, wherein R¹ or R² in each case can have identicalor different meanings, and n=0, 1 or 2.

For the preparation of these compounds, thiophosphoryl chloride orbromide is reacted with a mercaptosilane of the formula

R¹ _(n)(R²O)_(3−n)—Si—Alk—SH

with the abovementioned meanings.

Mercaptosilanes are expensive starting compounds, since as a rule theyare prepared from the corresponding chlorosilanes (EP 471 164 B1, DE-AS20 35 619, DE-PS 33 46 910, U.S. Pat. No. 3,849,471, GB-PS 1 102 251).

The disadvantage of these known processes is that expensivemercaptosilane is used as an educt for the preparation of theabovementioned phosphorus-containing compounds.

An object of the present invention is to provide an alternative processfor the preparation of sulfur- and phosphorus-containing organosiliconcompounds.

SUMMARY OF THE INVENTION

The above and other objects of the invention can be achieved by aprocess for the preparation of sulfur- and phosphorus-containingcompounds of the formula

[R¹ _(n)(R²O)_(3−n)—Si—Alk—S—]₃P═S,

in which Alk denotes an alkylene group having 1 to 10 carbon atoms, R¹,R² denote an alkyl group having 1 to 5 carbon atoms, a cycloalkyl grouphaving 5 to 8 carbon atoms, a phenyl group, a benzyl group or a2-methoxyethyl group, wherein R¹ or R² in each case can have identicalor different meanings, and n=0, 1 or 2, which is characterized in thathalogen-containing silanes of the formula

R¹ _(n)(R²O)_(3−n)—Si—Alk—Hal,

in which Alk denotes an alkylene group having 1 to 10 carbon atoms, R¹,R² denote an alkyl group having 1 to 5 carbon atoms, a cycloalkyl grouphaving 5 to 8 carbon atoms, a phenyl group, a benzyl group or a2-methoxyethyl group, wherein R¹ or R² in each case can have identicalor different meanings, Hal denotes a halogen, preferably chlorine orbromine, and n=0, 1 or 2, are reacted with phosphorus pentasulfide(P₄S₁₀) and a metal sulfide.

The reaction can take place according to the equation

The reaction can be carried out in a solvent, preferably hexane,acetonitrile, toluene, heptane or cyclohexane. Since phosphoruspentasulfide dissolves in R¹ _(n)(R₂O)_(3−n)—Si—Alk—Hal, the reactioncan be carried out without a solvent. The reaction can be carried outwith exclusion of air and moisture.

The reaction can be carried out under an inert gas, preferably nitrogen,argon or helium. The reaction can be carried out at temperatures of 20°to 300° C., preferably 150° to 250° C. Sodium sulfide (Na₂S), potassiumsulfide (K₂S) or ammonium sulfide ((NH₄)₂S) can be used as the metalsulfide.

The sulfur- and phosphorus-containing compounds prepared according tothe invention can be used in rubber mixtures.

DETAILED EMBODIMENT OF THE INVENTION Example

A mixture of 30.8 g (69.2 mmol) P₄S₁₀, 200.0 g (830.3 mmol)chloropropyltriethoxysilane and 32.4 g (415.3 mmol) sodium sulfide(Na₂S) is initially introduced into a 500 ml three-necked flask in anargon atmosphere and is heated to 200° C. After stirring at 200° C. for2.5 h, insoluble constituents are filtered off. All the volatileconstituents are removed in vacuo. 168.5 g (79% yield) oftetrathiophosphoric acid S,S,S-tris (triethoxysilylpropyl) ester areobtained as a pale yellow clear liquid.

¹H-NMR (CDCl₃): δ0.75 (m, ²J_(H—Si)=111.4 Hz, 6H, Si—CH ₂—CH₂—CH₂—S—),1.22 (t, ³J_(H—H)=7.4 Hz, 27H, CH ₃—CH₂—O—Si), 1.85 (dm, ³J_(H—H)=7.5Hz, 6H, Si—CH₂—CH ₂—CH₂—S—), 3.02 (dt, ³J_(H—H)=7.5 Hz, ³J_(H—P)=17.0Hz, 6H, Si—CH₂—CH₂—CH ₂—S—), 3.82 (q, ³J_(H—H)=7.4 Hz, 18H, CH₃—CH₂—O—Si). ³¹P-NMR (CDCl₃): δ94.5 (s)

Further variations and modifications of the present invention will beapparent to those skilled in the art from a reading of the foregoing andare intended to be encompassed by the claims appended hereto.

German patent application 199 54 815.3 is relied on and incorporatedherein by reference.

What is claimed is:
 1. A process for the preparation of a sulfur- andphosphorus-containing compound of the formula [R¹_(n)(R²O)_(3−n)—Si—Alk—S—]₃P═S, in which Alk denotes an alkylene grouphaving 1 to 10 carbon atoms, R¹, R² denote an alkyl group having 1 to 5carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, a phenylgroup, a benzyl group or a 2-methoxyethyl group, wherein R¹ or R² ineach case can have identical or different meanings, and n=0, 1 or 2,comprising reacting a halogen-containing silane of the formula R¹_(n)(R²O)_(3−n)—Si—Alk—Hal, in which Alk denotes an alkylene grouphaving 1 to 10 carbon atoms, R¹, R² denote an alkyl group having 1 to 5carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, a phenylgroup, a benzyl group or a 2-methoxyethyl group, wherein R¹ or R² ineach case can have identical or different meanings, Hal denotes ahalogen and n=0, 1 or 2, with phosphorus pentasulfide (P₄S₁₀) and ametal sulfide.
 2. The process for the preparation of a sulfur- andphosphorus-containing compound according to claim 1, wherein the metalsulfate is chlorine or bromine.
 3. The process for the preparation of asulfur- and phosphorus-containing compound according to claim 1, whereinthe metal sulfide is sodium sulfide (Na₂S), potassium sulfide (K₂S) orammonium sulfide ((NH₄)₂S).
 4. The process for the preparation of asulfur- and phosphorus-containing compound according to claim 1, furthercomprising carrying out the reaction in a solvent.
 5. The process forthe preparation of a sulfur- and phosphorus-containing compoundaccording to claim 1, further comprising reacting in the absence of asolvent.
 6. The process for the preparation of a sulfur- andphosphorus-containing compound according to claim 1, further comprisingreacting at a temperature of 150° to 250° C.